Gasket and dispensing head assembly for cartridge grease guns



Sept. 12, 1967 E. P. SUNDHOLM GASKET AND DISPENSING HEAD ASSEMBLY FOR CARTRIDGE GREASI; GUNS 2 Sheets-$heei Filed March 16, 1966 iii/e10 mum Sept. 12, 1967 E. P. SUNDHOLM GASKET AND DISPENSING HEAD ASSEMBLY FOR CARTRIDGE GREASE GUNS Filed March 16, 1966 2 Sheets-Sheet E Mann United States Patent M 3,341,085 GASKET AND DISPENSING HEAD ASSEMBLY FOR CARTRIDGE GREASE GUNS Edwin P. Sundholm, Albert City, Iowa 50510 Filed Mar. 16, 1966, Ser. No. 534,734 5 5 Claims. (Cl. 222-260) This application is a continuation-in-part of my copending prior application, Ser. No. 479,539, filed Aug. 13, 1965, and of my copending application, Ser. No. 444,156, filed Mar. 31, 1965, now Patent No. 3,300,100.

This invention relates to a gasket and dispensing head assembly for cartridge grease guns. More particularly the gasket and dispensing head assembly of the present invention are particularly adapted for use with cartridge grease guns employing the cartridge loading method described in my copending application Ser. No. 479,539, filed Aug. 13, 1965. A grease gun adapted for this novel cartridge loading method is also described in my copending application Ser. No. 444,156, filed Mar. 31, 1965.

Hand grease guns of the lever-operated or pistol grip types are widely sold and used in the United States. The older practice was to load such han-d grease guns from a bulk-source of grease either using pressure or suction to force the grease into the barrel during loading, or, in some cases, using hand packing of the barrel. More recently, the practice has developed of using cartridgepackaged greases. Many users routinely employ cartridge-packaged greases, and the loading of hand grease guns with grease cartridges is probably the loading procedure of choice for most presentday users, except for special greases which may not be available in cartridges.

Before the development of my novel loading method described in said prior applications Ser. No. 444,156 and 479,539, there was only one generally employed loading procedure for cartridge-packaged greases. In introducing a cartridge into the grease gun, the front end cap was removed, and the plunger assembly was manually withdrawn by means of the external plunger rod handle which is provided with a locking means for holding the plunger assembly in a retracted position in the rearward portion of the barrel. The rear and front end caps were then removed from the grease cartridge, and the grease cartridge was fully inserted in the barrel before replacing the front end cap. At times, this procedure proved both inconvenient and messy. The insertion of the grease cartridge with the front end cap removed could result in grease moving outwardly through the opening in the front end of the cartridge before the final end cap had been replaced and secured to the barrel. There was also the danger that the operating rod could become disengaged from its locked position, which could cause the plunger assembly to be thrust forwardly under the action of the spring. When this occurred, grease would almost certainly be forced out of the front end of the cartridge, with resultant inconvenience and discomfort to the person loading the gun. The grease could get on the hands and clothing of the person loading the gun, or on the exterior of the front cap or gun barrel so as to soil the hands or clothing of the person using the gun at a later time.

In my novel method, as described more fully in said application Ser. No. 479,539, the above problems are substantially eliminated. Further, there is no need to provide a plunger rod or other means for retracting the' plunger assembly from the rear of the gun prior to the 65 insertion of the grease cartridge. These advantages are provided by a procedure wherein the front cap is removed and the plunger assembly is permitted to move to a forward position in the barrel, the used or spent grease cartridge being removed. With the caps removed from the front and rear end of the grease-containing cartridge,

3,341,085 Patented Sept. 12, 1967 the rearward portion of the cartridge is inserted into the front end portion of the cylinder or barrel of the gun, the plunger assembly being at least partially inserted within the cartridge rearward portion, and the rest of the cartridge projecting outwardly beyond the front end of the barrel. As the next step in the method, the front cap (on which the dispensing head is usually mounted) is applied over the projecting front end portion of the cartridge. In this step, it is essential that at least the inner portion of the gasket means provided within the front cap sealingly engage the front end of the cartridge. This is usually facilitated by the fact that the front ends of the cartridge are provided with metal mounting rims, but conventional flat annular gaskets have not proven to be as effective as would be desired for forming the seal.

In accordance with my method, the insertion of the cartridge is then completed by forcing the barrel cap toward the barrel front end to cause the plunger assembly to move toward a rearward position as the cartridge moves into the barrel while maintaining the sealing engagement between the gasket lip and cap rim. Since it is desirable to provide a threaded engagement between the barrel front end and the front cap, usually the front cap is provided with internal threads which mate with external threads on the barrel front end. As part of the last step in the cartridge insertion, it is, therefore, desirable to screw the cap onto the barrel until the front end of the barrel sealingly engages the outer portion of the cap gasket. Since the insertion is preferably completed as one continuous movement with the sealing pressure between the cap gasket and the front end of the cartridge being maintained at all times, it is important that the internal threads of the cap be guided into correct alignment with the ex ternal threads of the barrel.

If the cap is slightly offset or cocked with respect to the barrel as they are brought into engagement during the cartridge insertion, the grease in the cartridge, which is now under pressure from the spring behind the plunger, may be forced out between the gasket and the cartridge front end, thereby losing one of the important advantages of my method. Also, where the threads of the two mating parts are not started into proper engagement, the threads may become damaged, and excessive Wear on the threads can result with repeated cartridge insertions.

It is, therefore, a general object of the present invention to provide a gasket and dispensing head assembly which facilitates the carrying out of my novel cartridge loading method. More specifically, it is an object to provide a gasket and dispensing head assembly which results in an improved seal between the dispensing head or cap portion thereof and the front end of the cartridge as the cartridge is being forced into the barrel of the gun again-st the spring-urged plunger assembly. Still another specific object is to provide a gasket and dispensing head assembly of the kind described which also serves to align and guide the dispensing-head as it is moved toward the front end of the barrel during the cartridge insertion. More particularly, the object is to provide a construction in which the internal threads of the cylindrical cap portion of the dispensing head are guided into mated alignment with the 1 external threads on the front end of the barrel, thereby facilitating the completion of the cartridge insertion and the attachment of the dispensing head to the barrel in one continuous movement. These and other objects, advantages, and results will be referred to and further discussed in the following detailed specification.

A related object is to provide a grease gun of the character described which has no plunger rod or other members projecting from the rear of the barrel, and which is therefore simpler in construction and more economical to manufacture. More specifically, it is an object to provide a plunger assembly in combination with the aforesaid gasket anrd dispensing head where the plunger assembly is so constructed and arranged that it retracts and inserts automatically as the gun is loaded with a grease-containing cartridge, thereby improving the loading procedure and making it easier and more convenient.

This invention is shown in illustrative embodiments in the accompanying drawings, wherein FIGURE 1 is a side elevational view of a grease gun embodying the present invention, the internal components of the gun being shown in section for purpose of clarity;

FIG. 2 is an enlarged fragmentary side elevational view of the forward portion of the dispensing head and forward portion of the grease gun of FIG. 1 as the dispensing head is moved toward the front end of the barrel during the insertion of a grease cartridge;

FIG. 3 is a side elevational view of another grease gun embodying the present invention, the barrel and certain portions of the head being shown in section; and

FIG. 4 is an enlarged fragmentary view of the front end portion of the grease gun of FIG. 3 and of part of the dispensing head, the parts being shown as they would appear.

just prior to the completion of the insertion of a grease cartridge by my novel method.

A detailed description of the construction and operation of the grease gun of FIGS. 1 and 2 is set out in copending application Ser. No. 444,156, filed Mar. 31, 1965, and entitled, Axially-Operated Hand Grease Gun. Except as required for an understanding of the present invention, the full and detailed disclosure of said application Ser. No. 444,156 will not be repeated herein. It will be understood that reference may be had to said application for supplementary information as may be desired.

Similarly, with respect to the grease gun of FIGS. 3 and 4, reference is made to copending application Ser. No. 570,463, filed Aug. 5, 1966, and entitled, Dispensing Head Assembly for Hand Grease Guns. A detailed description of the construction and operation of the grease gun of FIGS. 3 and 4 is set out in said application, and it is understood that reference may be had to supplement the present disclosure, which will be largely confined to the specific novel features of the invention claimed herein.

Looking first at the embodiment of FIGS. 1 and 2, it can be seen that the grease gun includes a cylindrical barrel having an open front end 11 (FIG. 2), a detachable dispensing head 12 having a rearwardly-extending cylindrical cap or mounting portion 13, and a plunger assembly 14 (FIG. 1) within barrel 10 which is movable from a position at the rear of the barrel, as shown in FIG. 1, to a position adjacent the front end thereof when the grease G is fully dispensed from the grease cartridge 15, or when an old grease cartridge has been removed prior to the insertion of a new cartridge. The forward end portion 16 of barrel 10 adjacent the front opening 11 is provided with an externally threaded portion 17. The rearwardly-extending portion 13 of dispensing head 12 is provided with internal threads 18 for cooperation with barrel threads 17 to permit the removal and attachment of the dispensing head 12. The plunger assembly 14 may be of the kind described in said application Ser. No. 479,539, but is preferably constructed as described in my copending application Ser. No. 449,538, filed Apr. 20, 1965, entitled Grease Gun Plunger Assembly. Since the particular construction of the plunger assembly is not directly related to the present invention, no detailed description will be set out herein. It will be noted, however, that plunger assembly 14 slides on rods 19, and that the plunger assembly is urged toward the forward end of the barrel 10 by a coil spring 20, which is indicated in compressed condition in FIG. 1.

As described in said application Ser. No. 444,156, the axially-operated grease gun of FIGS. 1 and 2 includes operating handles, such as the fixed handle 21 and movable handle 22 which are mounted on rear cap 23, which may be permanently affixed to the rear portion of barrel 10. The handles 21 and 22 are employed for imparting a reciprocating motion to the actuating rod 19 which has a piston 24 mounted on the forward end thereof for reciprocation within a piston guide 25 and a high pressure cylinder 26, the grease being admitted to cylinder 26 through inlet ports 27, and being discharged from the cylinder through the valve-controlled outlet port 28 to grease applicator pipe 29 and the grease fitting connector 30.

In accordance with the present invention, grease cartridge 15 is insertable in barrel 10 by extending the rear end portion of the cartridge through the barrel front end 11. As shown more clearly in FIG. 2, the front end edge portion 15a of cartridge 15 is provided with a mounting rim designated generally by 31. The rim 31, which is preferably formed of metal while cartridge is formed of paperboard, provides a central opening 32 for receiving a removable cap or lid (not shown). During shipment and storage of the grease containers, the removable cap will be in place within opening 32, and the rear end of the cartridge will usually be supplied with a removable slipon cover, which is completely removed prior to the insertion of the grease cartridge. As packed and shipped, the grease cartridge, such as the cartridge 15, will not be completely filled with the grease G, but a rearward portion of the cartridge adjacent the rear end will normally be left open or unfilled to permit the grease to expand. If, in the shipping, storage, or handling of cartridges, the grease has moved into the rearward position in the cartridge, the plunger assembly will be effective to move the grease forwardly as it is inserted within the rear end of the cartridge.

In the illustration shown in FIGS. 1 and 2, the front mounting rim 31 of cartridge 15 provides an outer annular attachment portion 33 which moves the front end edge portion 15a of the cartridge. The rim 31 also provides an inwardly-extending annular flange portion 34 surrounding the central opening 32. Preferably, rim flange portion 34 is rearwardly offset from the forward end of said rim attachment portion, as shown more clearly in FIG. 2. Flange 34 may advantageously provide an annular recess 35 adjacent attachment portion 33, and the inner wall 36 of attachment portion 35 may be in the form of a cylindrical wall extending between the attachment portion forward end and flange 34, or more particularly recess 35 thereof. It will be understood that attachment portion 33 is crimped to the cartridge front edge portion 15a, as indicated at 37.

As previously described, dispensing head 12 has a rearwardly-extending cylindrical mounting portion 13 which is dimensional and provided with internal threads for screwing onto the barrel forward portion 16. Head 13 provides an annular gasket seat 38 within and at the forward end of cylindrical portion 13 adjacent the outer end portion of threads 18, as shown more clearly in FIG. 2. Seat 38 receives and supports the annular gasket designated generally by the number 39. In accordance with the present invention, gasket 39 provides an outer annular portion 40 which bears against and sealingly engages the rim attachment portion 33, and also an inner annular portion 41 which bears against and sealingly engages the rim flange portion 34. Preferably, gasket 41 has an L- shaped or J-shaped cross section, the inner portion 41 providing a rearwardly-extending cylindrical portion 42. In the illustration shown in FIGS. 1 and 2, cylindrical portion 42 terminates in a rounded annular lip 43 which is received within recess 35 of flange 34. With this construction, the front edge of rim attachment portion 33 sealingly engages outer gasket portion 40, while lip 43 sealingly engages rim 34 within recess 35. It will be noted that cylindrical gasket portion 42 and lip 43 together provide a telescoping portion which is received Within the axially-concentric telescoping portion 35 of the rim 31. Preferably, as shown, the outer wall portion of lip 43 bears against the cylindrical wall 35, thereby assisting in centering, guiding, and stabilizing dispensing head 12 in relation to the front end portion of cartridge 15.

Going now to the embodiment of FIGS. 3 and 4, it will be seen that the parts of the gun having similar functions to those of the gun of FIGS. 1 and 2 have been given the same numbers except that the numbers have been primed. It will, therefore, be understood that the description of the general operation and construction of the grease gun of FIGS. 1 and 2 is also applicable to the grease gun of FIGS. 3 and 4. However, there are certain general differences in the construction of the gun of FIGS. 3 and 4, and these will now be briefly described.

The gun of FIGS. 3 and 4 is also the pistol grip type, but the movable operating handle 22 and its associated components are carried by dispensing head 12' rather than by rear cap 23'. The plunger assembly 14' is still slidable on guide rod 19', but the rod does not operate the piston in the high pressure cylinder. Instead, the piston 24' is directly actuated by handle 22, the piston moving into high pressure cylinder 26 to dispense the grease through valve-controlled port 28', which receives the grease from inlet port 27', suitable passages being provided within head 12', as shown, to connect to grease outlet pipe 29 and coupler 30'.

In the illustration shown, rear end cap 23' is permanently mounted on the rear end portion of barrel and the rear end of rod 19' extends through a central opening in the cap, being united thereto by a head 1%. The forward end of the rod is provided with a head 1% which limits the forward movement of plunger assembly 14' under the influence of spring 20. In the embodiment of FIGS. 1 and 2, the forward movement of the plunger assembly 14 is limited by the engagement with the rear end of piston 24, the piston being of slightly larger diameter than rod 19. The plunger assembly 14' is provided wtih a forward disc 14a, and a molded plunger cup 14b of resilient flexible material such as grease-resistant synthetic rubber. I

The gasket seat 38' provided by head 12 receives and supports the L-shaped gasket 39'. Head 12 also provides a rearwardly-extending cylindrical wall 38a, which extends around the inside of seat 38', thereby providing further support for gasket 39'. With the construction shown, gasket 39 is positively centered and maintained in a fixed relation on seat 38'. This permits the rearwardlyextending cylindrical gasket portion 42 to be maintained in exact axially-concentric relation with the cylindrical wall portion 35 of rim 31'. With the construction shown, the outer wall of gasket cylindrical portion 42 bears against the rim cylindrical wall 35', while the rearward end of gasket portion 42' bears against and sealingly engages rim flange 34. At the same time, the forward end of rim attachment portion 33 bears against and sealingly engages the outer annular gasket portion 40'. As previously indicated, the inner annular gasket portion 41, which provides the cylindrical gasket portion 42, extends inwardly to engage with the wall 38a. In other words, the outer portion of gasket 39' is snugly received within a recess provided by dispensing head 12'.

In the embodiment of FIGS. 3 and 4, the cylindrical rim wall 35" and the cylindrical gasket portion 42' provide cooperating positioning means for axially centering the dispensing head on the cartridge forward end portion. In effect, the rim portion 35' and the gasket portion 42' are axially concentric telescoping members to guide head 12' into threaded engagement with the barrel forward end portion as the cartridge is inserted. A similar function is performed by the corresponding parts of the embodiment of FIGS. 1 and 2. It will be understood that the telescoping portions of the gasket and cartridge rim should have a common axis so that the head mounting portion 13' is axially centered on the cartridge forward end portion. As in the embodiment of FIGS. 1 and 2, the rim flange 34 is rearwardly offset from the forward end of the rim attachment portion 33'.

Operation The operation of the present invention will .be largely apparent from the foregoing description. However, it may be briefly summarized as follows: When it is desired to load the grease gun with a new grease-containing cartridge, as may be required when the dispensing of the grease from an old cartridge has been completed, the dispensing head, such as the head 12 or 12, is unscrewed from the front of the barrel 10. If an old cartridge is in the gun, this is removed and discarded. Then a new cartridge, such as the cartridge 15 or 15', is started into the barrel. At this point, the plunger assembly 14 or 14' will be at the forward end of the barrel, being urged to this position by the spring 20 or 20. As the open rear end of the grease cartridge (the rear end cap having been removed) is started into the forward end of the barrel, the plunger assembly will begin to enter the rear end of the cartridge, holding the cartridge rear end in centered relation with respect to barrel 10. The rest of the cartridge will project forwardly from the barrel. The cylindrical mounting portion 13 or 13' will then be applied to the projecting forward end of the cartridge 15 or 15. Where the front mounting rim of the cartridge and the sealing gasket have the construction previously described with respect to rims 31, 31 and gaskets 39, 39', the sealing, centering, and guiding and advantages of the present invention will be substantially achieved.

With the dispensing head mounted on the front end of the cartridge, as shown for dispensing head 12 in FIG. 2, and dispensing head 12 in FIG. 4, the dispensing head will be centered with respect to the axis of the cartridge 15, which in turn will be centered with respect to the axis of barrel 10. Consequently, as the cartridge is thrust into the barrel, the cylindrical mounting portion 13 or 13' will be guided respectively onto the threaded front end portion of the barrel 16 or 16', thereby permitting the dispensing head to 'be screwed tightly onto the barrel with a minimum of waste motion and without damaging the threads of either member as part of the continuous motion of inserting the grease cartridge. At the same time, a highly effective seal is maintained between the gasket 39 or 39 and the rim flange 31 or 31'. It will be understood that the gaskets 39 or 39' are preferably formed of a flexible, resilient material, such as grease-resistant synthetic rubber. A sealing engagement can therefore be maintained between the inner portion 42 or 42 and the rim flange portion 31 or 31' at the same time as the sealing engagement is maintained between the rim attachment portion 33 or 33' and the outer gasket portion 40 or 40'. This double seal is of particular value during the insertion of the grease cartridge, but it also continues to 'be effective after the dispensing head 12 or 12 has been reattached to the barrel 10 or 10'.

In FIG. 2, the rim mounting portion 13' is shown during the later stages of the insertion as it begins to approach the threaded barrel portion 16. In FIG. 4, a still later stage in the insertion process is illustrated, the threads 18' just approaching the threads 17'. In FIGS. 2 and 4, the movement of the dispensing head 12 or 12 with respect to the barrel 10 or 10 is indicated by the arrows.

In the final stages of the cartridge insertion for the embodiment of FIGS. 1 and 2, the guiding of the dispensing head 12 into threaded engagement with the barrel 10 is further promoted by the entry of piston 24 into piston guide 25. These members in effect provide auxiliary guiding means.

With respect to the embodiment of FIGS. 3 and 4, it Will be noted that rod 19' terminates at rear cap 24', and is secured to the central portion of the cap by the head 19a. The retraction and insertion of the plunger assembly 14' is automatically obtained during the forcing of the cartridge 15 into the barrel 10'. No means is provided for retracting the plunger assembly 14' other than the cartridge insertion, while cap 23' comprises the rearwardmost part of the grease gun with no plunger rod or other operating members projecting outwardly therefrom.

While, in the foregoing specification, this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the grease gun art that the present invention is susceptible to additional embodiments, and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.

I claim:

1. A hand grease gun including the combination of:

a cylindrical barrel having an open front end for receiving a grease cartridge,

the forward end portion of said barrel providing external threads for connecting said barrel front end to a dispensing head;

a grease cartridge having an open rear end and being insertable in said barrel by extending said rear end through said barrel front end,

the front end edge portion of said cartridge being provided with a mounting rim for a removable closure, said rim having an outer annular attachment portion enclosing the said front end edge portion and an inwardly-extendingannular flange portion surrounding a central opening; and

a dispensing head having a rearwardly-extending cylindrical mounting portion received over said barre-l forward end portion,

said head mounting portion having internal threads adjustably engaging the threads of said barrel forward end portion, said head providing an annular gasket sea-t within said cylindrical portion at the forward end thereof;

wherein the improvement comprises an annular gasket of resilient, flexible material disposed within said cylindrical mounting portion and supported by said seat,

said gasket providing a laterally outer annular portion, and a laterally inner annular portion providing a rearwardly-extending cylindrical portion, said outer annular portion on its rearward side bearing against and sealingly engaging said rim attachment portion and also on its forward side bearing against and sealingly engaging said gasket seat, and said gasket cylindrical portion having a rearward side bearing against and sealingly engaging the forward side of said rim flange portion inwardly of said rim attachment portion;

whereby said head mounting portion is guided into threaded engagement with said barrel forward end portion as said cartridge is inserted, and the tightening of said head on said barrel achieves a double seal between said gasket and said cartridge rim.

2. In a cartridge loading grease gun, the combination of:

(a) a cylindrical barrel for receiving a grease-containing cartridge,

said barrel having a closed rear end and an openable front end through which the open rear end of said cartridge is inserted, the forward end portion of said barrel providing external threads for connecting said barrel front end to a dispensing head; (b) a dispensing head including operating means therefor removably mounted on said front end,

said head providing a rearwardly-extending cylindrical mounting portion received over said barre'l forward end portion and having internal threads adjustably engaging the threads of said barrel forward end portion, said head also providing an annular gasket seat within said cylindrical portion at the forward end thereof;

(c) a plunger assembly within said barrel,

said assembly being movable from the rearward portion to the forward portion of said barrel,

said assembly including a forward portion of smaller diameter than the internal diameter of said barrel which forward portion is dimensioned to enter said cartridge rear end,

said assembly also including an annular sealing portion and being formed of yieldable resilient material,

said sealing portion having an uncontracted diameter slightly greater than the internal diameter of said cartridge while being contractible when forced rearwardly by engagement with said cartridge rear end to a diameter corresponding to the cartridge internal diameter for insertion in said cartridge;

((1) spring means disposed within said barrel behind said plunger assembly,

said spring means yielda'bly urging said plunger assembly from said rearward barrel portion to said forward barrel portion while permitting said assembly to retract from said forward portion to said rearward portion as said cartridge is loaded,

said grease gun having no means for retracting said plunger assembly other than said cartridge loading and said plunger assembly retracting and inserting automatically as said gun is loaded with said grease-containing cartridge; and

(e) a sealing gasket of resilient material disposed within said cylindrical mounting portion and supported by said seat,

said gasket providing an annular portion arranged to sealingly engage the forward end portion of said cartridge to prevent the escape of grease therefrom as said cartridge is inserted.

3. The combination of claim 2 which also includes a guide rod for said plunger assembly, said rod being disposed within said barrel along the central axis thereof and extending through said plunger assembly, said assembly being slidable along said rod in guided relation therewith, and means at the rear of said barrel for fixedly supporting the rear end of said rod so that said rod is permanently positioned within said barrel, the front end of said rod projecting freely for insertion in said grease cartridge.

4. The combination of claim 3 wherein a cap is fixedly mounted on the said barrel rear end for closing said end, said cap comprising the rearwardmost part of said grease gun, the rear end of said rod terminating at said cap and being fixedly attached to and supported by the central portion of said cap without projecting rearwardly substantially beyond said cap.

5. In a cartridge loading hand grease gun, the combination of:

(a) a cylindrical barrel for receiving a grease-containing cartridge,

said barrel having a closed rear end and an openable front end through which the open rear end of said cartridge is inserted, the forward end portion of said barrel providing external threads for connecting said barrel front end to a dispensing head; (b) a dispensing head including operating means therefor removably mounted on said front end,

said head providing a rearwardly-extending cylindrical mounting portion received over said barrel forward end portion and having internal threads adjustably engaging the threads of said barrel forward end portion, said head also providing an annular gasket seat within said cylindrical portion at the forward end thereof; (c) a plunger assembly within said barrel,

said plunger assembly being movable from the rearward portion to the forward portion of said barrel, said assembly including a forward cylindrical guide portion of smaller diameter than the internal diameter of said barrel and which guide portion is dimensioned to enter said grease cartridge rear end, said assembly also including an annular sealing member disposed behind said cylindrical portion and being formed of yieldable resilient material, said sealing portion having a normal diameter at least as great as said barrel internal diameter while being contractible upon being forced rear- Wardly by engagement with said cartridge rear end to a diameter corresponding to the cartridge internal diameter; ((1) spring means disposed within said barrel behind said plunger assembly,

said spring means yieldably urging said plunger assembly from said rearward barrel portion to said forward barrel portion and said spring means comprising the only means for urging said plunger assembly forwardly, said grease gun having no means for retracting said plunger assembly other than said cartridge loading; (e) a cap fixedly mounted on the rear end of said barrel for closing said end,

said cap comprising the rearwardmost portion of said grease gun;

(f) a grease cartridge having an open rear end and being insertable in said barrel by extending said rear end through said barrel front end,

the front end edge portion of said cartridge being provided with a mounting rim for a removable closure, said rim having an outer annular attachment portion enclosing the said front end edge portion and an inwardly-extending annular flange portion surrounding a central opening; and

(g) an annular gasket of resilient, flexible material disposed within said cylindrical mounting portion and supported by said seat,

said gasket providing a laterally outer annular portion, and a laterally inner annular portion providing a rearwardly-extending cylindrical portion, said outer annular portion on its rearward side bearing against and sealingly engaging said rirn' attachment portion and also on its forward side bearing against and sealingly engaging said gasket seat, and said gasket cylindrical portion having a rearward side bearing against and sealingly engaging the forward side of said rim flange portion inwardly of said rim attachment portion.

References Cited UNITED STATES PATENTS 1,981,508 11/1934 Harris 222-256 2,277,824 3/1942 Franson 222326 ROBERT B. REEVES, Primary Examiner.

HADD S. LANE, Examiner. 

1. A HAND GREASE GUN INCLUDING THE COMBINATION OF: A CYLINDRICAL BARREL HAVING AN OPEN FRONT END FOR RECEIVING A GREASE CARTRIDGE, THE FORWARD END PORTION OF SAID BARREL PROVIDING EXTERNAL THREADS FOR CONNECTING SAID BARREL FRONT END TO A DISPENSING HEAD; A GREASE CARTRIDGE HAVING AN OPEN REAR END AND BEING INSERTABLE IN SAID BARREL BY EXTENDING SAID REAR END THROUGH SAID BARREL FRONT BED, THE FRONT END EDGE PORTION OF SAID CARTRIDGE BEING PROVIDED WITH A MOUNTING RIM FOR A REMOVABLE CLOSURE, SAID RIM HAVING AN OUTER ANNUALR ATTACHMENT PORTION ENCLOSING THE SAID FRONT END EDGE PORTION AND AN INWARDLY-EXTENDING ANNULAR FLANGE PORTION SURROUNDING A CENTRAL OPENING; AND A DISPENSING HEAD HAVING A REARWARDLY-EXTENDING CYLINDRICAL MOUNTING PORTION RECEIVED OVER SAID BARREL FORWARD END PORTION, SAID HEAD MOUNTNG PORTION HAVING INTERNAL THREADS ADJUSTABLY ENGAGING THE THREADS OF SAID BARREL FORWARD END PORTION, SAID HEAD PROVIDING AN ANNULAR GASKET SEAT WITHIN SAID CYLINDRICAL PORTION AT THE FORWARD END THEREOF; WHEREIN THE IMPROVEMENT COMPRISES AN ANNULAR GASKET OF RESILIENT, FLEXIBLE MATERIAL DISPOSED WITHIN SAID CYLINDRICAL MOUNTING PORTION AND SUPPORTED BY SAID SEAT, SAID GASKET PROVIDING A LATERALLY OUTER ANNULAR PORTION, AND A LATERALLY INNER ANNULAR PORTION PORVIDING A REARWARDLY-EXTENDING CYLINDRICAL PORTION, SAID OUTER ANNULAR PORTION ON ITS REARWARD SIDE BEARING AGAINST AND SEALINGLY ENGAGING SAID RIM ATTACHMENT PORTION AND ALSO ON ITS FORWARD SIDE BEARING AGAINST AND SEALINGLY ENGAGING SAID GASKET SEAT, AND SAID GASKET CYLINDRICAL PORTION HAVING A REARWARD SIDE BEARING AGAINST AND SEALINGLY ENGAGING THE FORWARD SIDE OF SAID RIM FLANGE PORTION INWARDLY OF SAID RIM ATTACHMENT PORTION; WHEREBY SAID HEAD MOUNTING PORTION IS GUIDED INTO THREADED ENGAGEMENT WITH SAID BARREL FORWARD END PORTION AS SAID CARTRIDGE IS INSERTED, AND THE TIGHTENING OF SAID HEAD ON SAID BARREL ACHIEVES A DOUBLE SEAL BETWEEN SAID GASKET AND SAID CARTRIDGE RIM. 